Fibrous nonwoven materials and fibrous nonwoven composite materials are widely used as products or as components of products because they can be manufactured inexpensively and can be made to have specific characteristics. One approach has been to mix thermoplastic polymer fibers with one or more types of fibrous material and/or particulates. The mixtures are collected in the form of fibrous nonwoven web composites which may be bonded or treated to provide coherent nonwoven composite materials that take advantage of at least some of the properties of each component. For example, U.S. U.S. Pat. No. 4,100,324 issued Jul. 11, 1978 to Anderson et al. discloses a nonwoven fabric which is generally a uniform admixture of wood pulp and meltblown thermoplastic polymer fibers. U.S. Pat. No. 3,971,373 issued Jul. 7, 1976 to Braun discloses a nonwoven material which contains meltblown thermoplastic polymer fibers and discrete solid particles. According to this patent, the particles are uniformly dispersed and intermixed with the meltblown fibers in the nonwoven material. U.S. Pat. No. 4,429,001 issued Jan. 31, 1984 to Kolpin et al. discloses an absorbent sheet material which is a combination of meltblown thermoplastic polymer fibers and solid superabsorbent particles. The superabsorbent particles are disclosed as being uniformly dispersed and physically held within a web of the meltblown thermoplastic polymer fibers. European Patent Number 0080382 to Minto et al. published Jun. 1, 1983 and European Patent Number 0156160 to Minto et al. published Oct. 25, 1985 also disclose combinations of particles such as superabsorbents and meltblown thermoplastic polymer fibers. U.S. Pat. No. 5,350,624 to Georger et al. issued Sep. 27, 1994 discloses an abrasion-resistant fibrous nonwoven structure composed of a matrix of meltblown fibers having a first exterior surface, a second exterior surface and an interior portion with at least one other fibrous material integrated into the meltblown fiber matrix. The concentration of meltblown fibers adjacent to each exterior surface of the nonwoven structure is at least about 60 percent by weight and the concentration of meltblown fibers in the interior portion is less than about 40 percent by weight. Many of the aforementioned admixtures are referred to as "coform" materials because they are formed by combining two or more materials in the forming step into a single structure.
Coform engineered composites can be used in a wide variety of applications including absorbent media for aqueous and organic fluids, filtration media for wet and dry applications, insulating materials, protective cushioning materials, containment and delivery systems and wiping media for both wet and dry applications. Many of the foregoing applications can be met, to varying degrees, through the use of more simplified structures such as absorbent structures wherein only wood pulp fibers are used. This has commonly been the case with, for example, the absorbent cores of personal care absorbent products such as diapers. Wood pulp fibers when formed by themselves tend to yield nonwoven web structures which have very little mechanical integrity and a high degree of collapse when wetted. The advent of coform structures which incorporated thermoplastic meltblown fibers, even in small quantities, greatly enhanced the properties of such structures including both wet and dry tensile strength. The same enhancements were also seen with the advent of coform wiping sheets.
Many of the items or products into which coform materials are incorporated are generally regarded as being limited use disposable products. By this it is meant that the product or products are used only a limited number of times and in some cases only once before being discarded. With increasing concerns over waste disposal, there is now an increasing push for materials that are, for example, either recyclable or disposable through other mechanisms besides incorporation into landfills. One possible alternative means of disposal for many products, especially in the area of personal care absorbent products and wipers, is by flushing them into sewage disposal systems.
The very reason why many coform materials provide increased benefits over conventional materials, i.e., the meltblown thermoplastic fiber matrix, is the same reason why such materials are more difficult to recycle or flush. Many wood pulp fiber-based products can be recycled by hydrating and repulping the reclaimed wood pulp fibers. However, in coform structures the thermoplastic meltblown fibers do not readily break-up. The meltblown fibers are hard to separate from the wood pulp fibers, and they remain substantially continuous thereby giving rise to the possibility of dogging or otherwise damaging recycling equipment such as repulpers. From the standpoint of flushability, the current belief is that to be flushable, a product must be made from very small and/or very weak fibers so that the material will readily break-up into smaller pieces when placed in quantities of water such as are found in toilets and, again due to the nature of the fibers, when flushed will not be entrained or trapped within the piping of conventional private and public sewage disposal systems. Many of these systems, especially sewer laterals, may have many protrusions within the pipes such as tree roots which will snag any type of material which is still relatively intact. Such would be the case with conventional non-water-degradable meltblown thermoplastic fibers in coform materials. As a result, for at least the foregoing reasons, there is a need for a coform material which has the potential for being more user friendly with respect to recycling processes and disposal through alternative means to landfills such as, for example, flushing. Accordingly, it is an object of the present invention to provide such a material.